Alkali Metal Doped Organic Molecules on Insulators: Charge Impact on the Optical Properties

Doping-induced absorption changes of organic molecules on an insulating solid are reported. The charge transfer between alkali metal atoms and individual molecules on a surface leads to new electronic transitions identified with optical absorption spectroscopy. Progressive doping allows the discrimination of neutral, monoanionic and dianionic molecules in the solid state through examination of the spectra and rate equation modeling.